CHiral bis-benzo[1,2-b:4,3-b’]dithiophenes : synthesis and stereochemical properties

Thiophene-containing fused aromatic compounds are an interesting class of π-conjugated systems with applications in functional organic materials.1 Among them, benzo[1,2-b:4,3-b’]dithiophene (BDT) and its derivatives are widely studied in the field of materials science,2 and for photovoltaic applications.3 Moreover, BDT is a key intermediate for the synthesis of inherently chiral helical systems such as tetrathia[7]helicenes.4 In our ongoing studies on the synthesis and functionalization of BDTs,5 we have developed a novel and convenient route to prepare an interesting class of chiral heterobiaryl bis(benzo[1,2-b:4,3-b’]dithiophene) systems 2 and 3 (Figure 1). In this communication we will report the synthesis of compounds 2 and 3 along with the study of their chiroptical properties. Bromides 3 are also expected to have potential applications in asymmetric reactions, including the enantioselective synthesis of tetrathia[7]helicene derivatives.